Solutions

Line 5 is: Scare(hagrid,dudley).
Functors always have to be atoms, but atoms cannot start with a capital letter.
Correction: scare(hagrid,dudley).

Line 11: hate(uncle vernon,X) :- magical(X).
Atoms cannot contain spaces (and neither can variables, by the way) unless the whole atom is enclosed in single quotes. So, the problem is uncle vernon.
Correction: hate(uncle_vernon,X) :- magical(X). or hate('uncle vernon',X) :- magical(X).

Line 14: hate(aunt_petunia,X :- magical(X).
The head of the rule (what comes before :-) should be a complex term. All arguments have to be between an opening and a closing parenthesis. In Line 14, the closing parenthesis is missing.
Correction: hate(aunt_petunia,X) :- magical(X).

Line 17: hate(aunt_petunia,X) :- scare(X,dudley)
All clauses (facts and rules) have to end with a full stop. In Line 17, this full stop is missing.
Correction: hate(aunt_petunia,X) :- scare(X,dudley)

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